During the last decades, land subsidence has occurred in three main river deltas of China, especially in some metropolitans. With the assistance of some geodetic technologies, such as digital leveling, GPS, total station, and so on, repeat-pass radar interferometry has the capability to monitor land subsidence in 3 dimensions with high accuracy. The potential and limitation of repeat-pass radar interferometry are still being evaluated till now. Considering the operational application of this technique, this paper describes applications of D-InSAR the urban subsidence of China. The case study with a small data stack in Hong Kong presents about 1cm height change in two test sites. The two test sites have mainly been investigated, and some of the key steps of this technique have been discussed in detail. The evolution of the D-InSAR and the future research involve more accurate and robust measurement with large data stacks in a long time series.